Cardiovascular disease is a large, growing health problem world wide. Some studies indicate that approximately 15% of the Western World suffers from one or more cardiovascular disease. In the United States, nearly 25% of the population is affected, resulting in more than six million hospitalizations every year.
Various devices exist for monitoring certain parameters relating to cardiac performance. In some instances, in vivo parameters of a patient may need to be monitored over a period of time; for example, such monitoring may be necessary in a subject who has occasional irregular cardiac beats. Heart arrhythmias are changes in the normal sequence of electrical impulses that cause the heart to pump blood through the body. As such abnormal heart rhythms may only occur sporadically, continuous monitoring may be required for detection. By providing continuous monitoring, medical personnel determine if there is a tendency for production of sustained irregular beats in a life-endangering fashion. Medical personnel also use the monitoring results to establish a proper course of treatment.
One prior art device that measures heart rate is the “Reveal” monitor by Medtronic (Minneapolis, Minn., USA). This device comprises an implantable heart monitor used, for example, in determining if syncope (fainting) in a subject is related to a heart rhythm problem. The Reveal monitor continuously monitors the rate and rhythm of the heart for up to 14 months. After waking from a fainting episode, the subject places a first recorder device external to the skin over the implanted Reveal monitor and presses a button to transfer data from the monitor to the recorder. The subject gives the first recorder to a physician who provides the subject with a second recorder to use for continued data acquisition. The physician then analyzes the information stored on the first recorder to determine whether abnormal heart rhythm has been recorded. The use of the recorder is neither automatic nor autonomic, and therefore requires either the subject to be conscious or another person's intervention.
Another known type of implantable monitoring device is a transponder-type device, in which a transponder is implanted in a patient and is subsequently accessed with a hand-held electromagnetic reader in a non-invasive manner. An example of the latter type of device is described in U.S. Pat. No. 5,833,603.
In many circumstances, medical personnel are interested in collecting a variety of different types of data relating to the behaviour of the heart and the condition of the patient. Moreover, as mentioned above, it is desirable to obtain as much relevant data as possible without requiring the patient to visit health care provider. Relevant information may include the oxygen saturation level of blood flowing through the aorta, blood pressure, heart rate, blood flow, stroke volume, cardiac output, the electrical activity of the heart (for generating electrocardiogram (ECG) data), and body temperature.
An integrated heart monitoring device for acquiring signals and transmitting data is disclosed herein. In one embodiment of the invention, the monitoring device includes an optical sensor assembly including a plurality of photon emitters and a plurality of photon detectors for detecting a plurality of optical signals. The emitters and detectors face the aorta. A computing device operates the plurality of emitters and detectors and processes the plurality of optical signals to obtain optical measurement values representing the location and size of the aorta and the oxygen saturation of the blood flowing through the aorta.
The monitoring device further includes a Doppler sensor for emitting and detecting a plurality of ultrasonic waves. The computing device also operates the Doppler sensor and, with the aid of the optical measurement values obtained using the optical sensor assembly, processes the plurality of ultrasonic waves to obtain Doppler measurement values representing heart rate, blood flow, stroke volume, blood pressure, and cardiac output.
The monitoring device further includes an ECG sensor for detecting the electrical signals which cause the heart to pump. Additionally, the monitoring device includes a temperature sensor for measuring the temperature of the patient. An energy storage device powers the computing device, the various sensors, and a communication device which is configured to transmit the collected data, or information relating to the collected data, according to a predetermined schedule or upon the occurrence of an event, such as abnormal data or a request for data from an external device. The sensors, the computing device, the communication device, and the energy storage device are enclosed in a housing, which may be worn by the patient or implanted.
By integrating the plurality of sensors and other components mentioned above, embodiments of the present invention permit a single device, mounted at one location on the patient's body, to accurately measure a comprehensive set of parameters relating to the behaviour of the heart, including cardiac output. Moreover, the integrated monitoring device described herein may perform analyses of the parameters and perform functions in response to the “on-board” analyses, as opposed to other sensing devices that export raw data for analysis by another device. As indicated above, the integrated monitoring device according to embodiments of the invention also communicates with other devices, wirelessly or otherwise, providing information and receiving commands and data. As such, the monitoring device collects, analyzes, and communicates data without any human intervention.
The features of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings.
Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention. The exemplifications set out herein illustrate embodiments of the invention in several forms and such exemplification is not to be construed as limiting the scope of the invention in any manner.